1, the fault situation
A 50-type double rocker wheel loader is prone to slower steering during slow steering and lower steering when turning sharply under working conditions. Since the loader often uses the emergency steering to improve the work efficiency, the steering sink will increase the driver's labor intensity, which will easily cause the driver to fatigue and affect the work efficiency. Therefore, the loader should avoid the sudden steering phenomenon in the large throttle state. . In response to the problem of steering sinking, the prototype was subjected to slow steering and steering steering during the steering process, and the steering pressure was able to reach the specified pressure value.
2, cause analysis and troubleshooting
According to the principle of the steering system of the loader, the steering force depends on the magnitude of the resistance torque of the tire and the ground. Through the reasonable optimization of the steering hydraulic system, the force reflected on the steering wheel and the force used by the operator are the detected steering forces. The steering force is related to the flow of the steering gear. When the steering wheel is rotated at a low speed, the flow rate of the steering gear depends on the opening degree of the spool. As the rotational speed increases, the opening degree of the spool gradually increases. Small, when the maximum flow of the steering gear is reached, that is, the steering valve spool is fully opened, and the steering force is minimized. To achieve the fast and light steering effect, it also depends on the matching of the operating speed and flow rate, and also depends on the flow of the pipeline. When the pipe diameter is small, it acts as a throttle valve, and in severe cases, it can also affect the steering. Speed and steering force.
First check if the steering system pressure reaches the specified value. After testing, the steering pressure can reach the specified pressure value, which means that the sudden steering is not caused by the pressure. In addition, it is only possible that the fuel supply rate is low and the passive steering causes the sudden steering to sink. That is, the speed of the oil supplied to the steering cylinder cannot be satisfied by the speed of the oil supplied to the steering cylinder during the sudden steering, thereby causing the sudden steering.
After analyzing the hydraulic components of the steering system, the reasons for the low steering rate of the hydraulic steering system are as follows:
(1) There is air in the steering hydraulic system;
(2) The hydraulic oil tank has a low oil level and the pump oil absorption is insufficient;
(3) The filter element is clogged, so that the hydraulic oil tank does not flow smoothly, which makes the pump difficult to suck;
(4) The priority valve spool is stuck and cannot be fully opened;
(5) The steering gear used is not enough;
(6) The displacement of the steering pump is insufficient;
(7) The steering pipe diameter is too small.
For the above reasons, check the cause of the failure one by one:
(1) Exhaust treatment of hydraulic system: the steering gear is driven to the limit position, and the hydraulic pressure is discharged through the fuel tank; the bleeder bolt of the left steering cylinder is unscrewed, then the left steering is turned, and the left cylinder is large. The gas in the chamber is removed; the same method is used to check the gas in the small chamber and the gas in the other cylinder;
(2) adding hydraulic oil to the specified position;
(3) cleaning the filter element;
(4) cleaning the priority valve;
(5) Checking the displacement of the steering gear;
(6) Check the steering pump displacement.
After the above analysis and investigation, the problem of steering sinking has not been solved, indicating that the small diameter of the pipeline is the main factor causing the sudden steering sink, and it is decided to increase the diameter of the steering pipeline.